N4KN

The pilot stated that as the glider reached flying speed it began to oscillate with the right wing dipping and impacting the grass runway, which resulted in a loss of control. The tow line disconnected, as designed, and the glider came to rest in an inverted position. The pilot sustained minor injuries. A post-accident examination conducted by a Federal Aviation Administration inspector revealed substantial damage to the wings and the vertical stabilizer. The pilot reported there were no mechanical malfunctions or anomalies with the glider that would have precluded normal operation.